When you create a movie in iMovie you need to export the file with Expert Settings for it to play in MediaShout.  This will provide more options for different codecs that you can use.  After creating your movie you need to go to File>Export and select Expert Settings in the Compress movie for: option.  Select Share and iMovie will give you a list of Export formats at the bottom to choose from.  You can experiment with these and find one that works best for your situation.

Here are some recommended formats:

1. Movie to iPod
2. Movie to QuickTime Movie  (Go to Options>Video>Settings for specific codec options.  Some codecs that can work in MediaShout are Sorenson 3, H.264, and MPEG-4.)
3. Movie to AVI
4. Movie to MPEG-4
5. Movie to MPEG2
6. Movie to Windows Media

NOTE:  MediaComplete is not affiliated with Apple/iMovie and does not provide technical support for their products or services.